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It's June--the month school gets out, and the month we really get out into the sun. Which means that we really need to get out the sunscreen--and use it well.

As wonderful as the sun is, too much exposure can lead to skin cancer. Experts especially warn that burns during the younger years can raise the risk of skin cancer later in life--so it's really important that parents do everything they can to prevent those sunburns. Trying to limit in-the-sun activities during the peak sun hours of 10 am to 4 pm is a good start, as is wearing hats and trying to stay covered--but on a beach day or at day camp, neither may be possible. That's where sunscreen comes in.

How smart are you about sunscreen? Try out this quiz and see:

Which of the following words shouldn't be on a sunscreen label?

a. sunblock

b. waterproof

c. both of the above

Answer: c. No sunscreen can completely block the sun--or stay on despite any sweating or swimming. That's one of the reason the FDA has changed labeling rules--so that companies will stop telling us lies.

You have some sunscreen left over from last summer. You should:

a. Use it. Why waste it?

b. Chuck it and buy new sunscreen

c. Use it if the expiration date hasn't passed

Answer: b--with one small caveat. Sunscreen is supposed to have a shelf life of 3 years so might not have an expiration date--but even if you just bought it last year, you don't know how long it was on a shelf somewhere. Theoretically you can use sunscreen that hasn't passed the expiration date on the label--but high temperatures can make sunscreen less effective. So unless that unexpired sunscreen has sat in a cool place since you bought it (the caveat), chuck it and buy new stuff.

Answer: false, at least after 30. You should buy at least SPF 30 (the Consumer Reports folks say 40 based on their tests--apparently some of the 30's aren't exactly 30), but there is just no need to buy the 50+ stuff--you really don't get more protection from it.

If the sunscreen says "water-resistant", how often should you reapply it if your kids are getting wet (or sweating)?

a. Every 2 hours

b. According to the instructions on the label

c. You don't have to reapply--it's water-resistant

Answer: b--or a. The label should tell you how often to reapply. If it doesn't, reapply at least every 2 hours (even if nobody is playing in the water!)

True or false: In order to protect against mosquitoes and ticks, it's a good idea to buy a sunscreen that has insect repellent in it too.

Answer: c. An ounce is what you should use for the average adult or large kid. Smaller kids might use a little less, but you really want to thoroughly cover all exposed skin. While theoretically you don't need to cover areas covered by one of those swim shirts that blocks UV rays, I always do anyway--because sometimes those shirts end up coming off! Try to put on the sunscreen before you leave the house, to prevent the squirming and running away from you that often happens at the beach or park. When my kids were little, I always put it on when they were naked, before I put on their suits. That way I could be sure I didn't miss any spots!

Speaking of which, that's the problem with spray sunscreens--it's hard to know if you missed a spot. Or got enough on. And there are concerns that inhaling them by accident isn't good for you. So it's best not to use them.

True or false: there is controversy over whether some common sunscreen ingredients could be toxic.

Answer: sadly,true. There are worries that oxybenzone and retinoids, as well as nanoparticles, could possibly have health risks. The Environmental Working Group has come out against them (and has a list of sunscreens that do not contain them)--but interestingly, the American Academy of Dermatology disagrees, saying that there's no good evidence that they are dangerous. Here's what we do know: too much exposure to UV rays can cause cancer. There are risk-benefit ratios to lots of the decisions we have to make for and about our children, and this is one of them. Please, don't ever skip the sunscreen because you are worried about the ingredients.

About MD Mama

Claire McCarthy, M.D., is a pediatrician and Medical Communications Editor at Boston Children's Hospital . An assistant professor of pediatrics at Harvard Medical School and a senior editor for Harvard
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